a random number generator
the first prime
the second prime
the exponent
if specified, this has to be d with exp * d = 1 mod (p - 1, q - 1). Leave it as 0 if you wish the constructor to calculate it.
if specified, this must be n = p * q. Leave it as 0 if you wish to the constructor to calculate it.
Construct a private key from the specified parameters.